A Net ZEB Case Study—Experiences from Freezing in Ventilation Heat Exchanger and Measured Energy Performance

Net Zero Energy Buildings constitute one measure to reduce energy use and increase use of energy from renewable sources. Hence, it is important share knowledge and experiences from completed projects. This case study show that it is possible to build Net Zero Energy Buildings with existing techniques. However, a common strategy to prevent or limit the build-up of ice and frost in ventilation heat exchangers, Supply fan shut off, were not suitable this project, since it is air tight buildings. After occurring problems in the first winter, ventilation pre-heater were installed to prevent the build-up of ice and frost. Thanks to placement of temperature sensor after the pre-heater, the increased energy use for pre-heater may be expected to be low, roughly 1 kWh/m2a.